Disk drive devices using various kinds of disks, such as optical disks, magneto-optical disks, flexible magnetic disks and the like have been known in the art. In particular, hard disk drives (HDDs) have been widely used as storage devices of computers and have been one of indispensable storage devices for current computer systems. Moreover, the HDDs have found widespread application to moving image recording/reproducing apparatuses, car navigation systems, cellular phones, and the like, in addition to the computers, due to their outstanding characteristics.
A magnetic disk used in an HDD has multiple concentric data tracks and multiple servo tracks recorded discretely in the circumferential direction. Each data track includes multiple data sectors containing user data. Servo data have address information. A head element portion of a head slider supported by a swinging actuator accesses a desired data sector in accordance with address information in servo data to write data to and retrieve data from the data sector.
A head slider flies above a rotating magnetic disk. Contaminants deposited on the air bearing surface (ABS) of the head slider may cause data loss such as a write fault or an unreadable error. These errors seem to be partly caused by higher fly-height of the head slider due to the adhesion on the ABS or an enormous variation in the head fly-height because of contact of the head slider with the magnetic disk through the adhesion.
The above-described contaminants are mainly organic materials. Organic materials vaporizing from the components packaged in an enclosure may condense to deposit on the ABS, or may condense to deposit on the magnetic disk and then adhere to the ABS of the head slider flying over the magnetic disk. Certain components may be the origin of the organic materials. For example, in winding a VCM coil of the actuator, wax is coated on a copper wire so that a short circuit will not be brought up resulting from an enamel coating of the copper wire being peeled off. The adherent wax remains on the VCM coil in the HDD. The wax vaporizes at high temperature or due to the heat generated by the VCM coil during a seek operation.
For another example, organic materials vaporizes from resin components such as a ramp or adhesives at operational temperature of an HDD and deposit onto the surface of the magnetic disk when the temperature drops during non-operation. The head slider flying above the rotating magnetic disk gradually gathers organic materials dispersed on the magnetic disk onto its ABS. If the adhesion on the ABS increases, the head fly-height may increase, or the adhesion may fill the clearance between the head slider and the magnetic disk at some timing and the head slider may contact the magnetic disk through the adhesion, resulting in that the head slider rides on the adhesion to increase the fly-height. These seem to cause data loss such as a write fault and an unreadable error.
So far, a technique has been proposed that removes the adhesion on the ABS (for example, refer to a Japanese Patent Publication No. 8-279120 “Patent Document 1”). The head slider according to this conventional technique comprises a heater element and the heat by the heater element vaporizes lubricant on the ABS. This prevents an adsorption phenomenon between the head slider and the magnetic disk due to the lubricant on the ABS.
The above related art document indicates that, in an HDD employing the contact start and stop (CSS) scheme, feeding electric current across a heating element immediately after a stop of the disk effectively prevents the adsorption phenomenon. However, when the head slider is in contact with the magnetic disk, it is difficult to remove the adhesion on the head slider by vaporizing it completely using the heating element. Similarly, while the head slider is flying above the magnetic disk, it is difficult to remove the adhesion on the head slider by vaporizing it completely using the heating element, too.
This is because, if the head slider is in contact with the magnetic disk or it is flying several nanometers above the magnetic disk with high pressure air present between the head slider and the magnetic disk, the heat on the surface of the head slider is conducted to the magnetic disk so that it is necessary to supply the head slider with a large amount of heat to raise the temperature on the surface of the head slider high enough.
As seen from the above, it is important to effectively raise the temperature on the surface of the head slider to remove the adhesion on the head slider. On the other hand, it is important to consider the reliability of the head slider. Temperatures exceeding a specific value will cause element destruction in the head element portion on the head slider. Especially, due to a tendency toward higher recording density and smaller head element portion, the thermotolerance of the head element portion decreases more than ever. Accordingly, it is important that the temperature of the head element portion should not rise too high when removing the adhesion on the head slider.